The present invention relates to modified rosin esters. The modified rosin ester compounds of the present invention can be represented by the following structural formula: ##STR1## wherein R is hydrogen, alkyl containing from about 8 to 22 carbon atoms, hydroxyalkyl containing from about 8 to 22 carbon atoms, sorbitan monoesters of fatty acids containing from about 8 to 22 carbon atoms or alkyl phenoxy containing from about 8 to 22 carbon atoms; X is hydrogen or an alkali metal salt such as Na, K, Mg or Ca; A is CH.sub.2 --CH.sub.2 --O or ##STR2## an n is an integer of at least 4 and preferably from about 4 to 5000.
The modified rosin esters of the present invention can be prepared by reacting the levopimaric acid isomer of abietic acid of the formula: ##STR3## with maleic anhydride of the formula: ##STR4## to form a maleated rosin intermediate of the formula: ##STR5## The reaction of the abietic acid with the maleic anhydride is carried out in the presence of a suitable nonprotic solvent such as toluene, xylene, ethyl benzene, and the like and is carried out at a temperature of from about 100.degree. C. to the boiling point of the solvent that is employed.
The maleated rosin intermediate is then reacted with a nonionic surfactant of the formula EQU HO--A].sub.n R
wherein R, A and n are as previously defined; to form the desired compounds of the present invention. The reaction of the maleated rosin intermediate with the nonionic surfactant is carried out in the presence of a suitable nonprotic solvent such as toluene, xylene, ethyl benzene and the like and is carried out at a temperature of from about 100.degree. C. to the boiling point of the solvent that is employed.
Specific examples of the novel compounds of the present invention include: ##STR6## wherein R is sorbitan monopalmitate ##STR7## wherein R is sorbitan monolaurate ##STR8## wherein R is sorbitan monococoate ##STR9## The novel modified rosin ester compounds of the present invention exhibit excellent surfactant properties. These compounds exhibit the desirable cleansing properties and easy "spreadability" and processing characteristics of anionic surfactants while unexpectedly also exhibiting the mildness characteristics of nonionic surfactants. Such is, as stated, unexpected because rosinated materials are normally irritating to the eyes and skin. The excellent "spreadability" characteristics of these modified rosin ester compounds permit them to be extremely useful in gel-type hair care formulations as well as in creme and lotion formulations.
The following examples illustrate the present invention but are not to be construed as imposing any limitations thereon.